Approaches to Assessing Viability and Developing Recovery Criteria for Threatened Puget Sound Steelhead

            In response to continued declines in steelhead populations throughout Puget Sound, steelhead from the Canadian border to the Elwha River were listed as threatened under the U.S. Endangered Species Act on 11 May 2007.  Efforts to assess the status of the Puget Sound steelhead Distinct Population Segment (DPS) and initiate the recovery process have been hampered by the limited information available relative to many Pacific salmon species and the differences in life histories between iteroparous steelhead and semelparous salmon.

            In contrast to Chinook salmon, steelhead abundance estimates for Puget Sound are largely limited to redd counts in index reaches and genetic sampling is available for half of the presumptive populations.  Steelhead spawn from January to June, when river conditions are often poor for spawning surveys.  Steelhead also spawn in a variety of habitats, from small tributaries and side channels to larger rivers.  Additionally, being iteroparous steelhead do not leave carcasses for inventory purposes or life history assessment (scale collection).  Puget Sound steelhead have been managed as a game fish since the 1920s with almost all of the fisheries catch taken in terminal areas.  Thus, there has been little need for population identification (i.e. genetic sampling or CWT marked fish).  Lastly, the relationship between anadromous steelhead and resident rainbow trout is poorly understood, but there is unquestionably some level of interaction and migration between the two-life history forms.

            In developing recovery criteria for Puget Sound steelhead the Technical Recovery Team has attempted to adapt the work done by other Recovery Teams along the West Coast.  Recovery criteria need to reflect our current level of knowledge for Puget Sound steelhead.  In contrast to recovery criteria for other listed DPSs and ESUs which have become increasingly complex, we have developed simplified viability models that take into account the considerable uncertainty inherent in most of the information.  In addition, these criteria need to consider possible future conditions, especially in respect to climate change and land development in the Puget Sound corridor.